Transportation equipment window antireflection film, glass with antireflection film, laminated glass and production method therefor

ABSTRACT

An antireflection film for a window of a transport, which comprises a light absorbing film consisting essentially of a nitride and having a film thickness of from 3 to 12 nm, and an oxide film having a refractive index of from 1.45 to 1.70 and a film thickness of from 70 to 140 nm, formed in this order on a substrate, and which has adequately low reflection performance to the oblique incident light, an adequate abrasion resistance and a high transmittance of visible light, a glass provided with said film, a laminated glass and its production process.

This application is a 371 of PCT/JP99/06653, filed Nov. 29, 1999.

TECHNICAL FIELD

The present invention relates to an antireflection film for a window ofa transport, a glass provided with an antireflection film for a windowof a transport, a laminated glass provided with an antireflection filmfor a window of a transport and its production process. Particularly, itrelates to a light absorptive antireflection film which reducesreflection of oblique incident light, a glass for an automobile usingsaid antireflection film, a laminated glass for an automobile and itsproduction process.

BACKGROUND ART

Conventionally, since the reflectance of visible light (hereinafterreferred to simply as reflectance) from the film face side (interiorside) of a windshield of an automobile is high, the color tone of e.g.the interior has been limited to one based on dark tone color (such asblack), in order to suppress reflection of the dashboard and itssurrounding, and to increase visibility of the driver. That hassignificantly restricted, the color of the car interior, andsignificantly limited the design of an automobile.

In recent years, the setting angle of a windshield tends to be acute,from the viewpoint of the appearance design, and accordingly, theproblem of the reflection on the interior face tends to be moresignificant.

Accordingly, it has been required to reduce the reflectance on theinterior face of a windshield and to increase the allowable range of theinterior design.

As a method to achieve such requirements, it has been known to form anantireflection (hereinafter sometimes referred to simply as AR) film onthe surface of a windshield. For example, the following methods suchas 1) a method of forming a transparent multi-layer AR film, and 2) amethod of forming a transparent single-layer AR film, have beenproposed.

The method 1) is to form a known multi-layer AR film by vacuumdeposition or sputtering. However, since the total film thickness is sothick as at least about 250 nm, the cost required for the production ishigh, and further, coating is required on both inside and outside thecar to obtain an adequate AR function, such being problematic. Further,since the outside of the car is always abraded by wipers, an extremelyhigh abrasion resistance is required, but the abrasion resistance isinadequate with conventionally known film materials.

In the method 2), in the case of the vacuum deposition, MgF₂ may becoated. However, it is necessary to form a film on a hot substrate inorder to let MgF₂ have an adequate strength, and stability of the filmthickness distribution which is characteristic of the deposition isinadequate, such being problematic in productivity. Further, the problemof the abrasion resistance on the outside of the car is similar to thecase of the method 1). In recent years, a single-layer AR film having ahigh strength has been developed by using porous SiO₂ (porous siliconoxide). However, the abrasion resistance on the outside of the car isinadequate, and dirt attached to the pores during long-term use is lesslikely to be removed.

On the other hand, as a low-reflection film for CRT, a new typemulti-layer AR film comprising a light absorbing film as a constituenthas been proposed (JP-A-64-70701, U.S. Pat. No. 5,091,244). With thismulti-layer AR film, the visible reflectance on the surface can be made0.3% or less, the sheet resistance of the surface can be made 1 kΩ/□ orless, and further, the electromagnetic wave-shielding effect can beimparted. Further, since a light absorbing film is used, the entiretransmittance of visible light (hereinafter sometimes referred to simplyas transmittance) will decrease, whereby the contrast can be increased.However, if this multi-layer AR film for CRT is directly applied to awindshield for an automobile, the desired effect can rarely be obtained.Namely, as mentioned above, a windshield for an automobile is set in asignificantly slanted state, and accordingly, with the film constitutionfor CRT which is designed for incident light at right angles, noadequate AR performance will be obtained, or the reflection color tonetends to be yellowish or reddish, such being problematic.

Further, a windshield for an automobile is required to shield the directsolar radiation light as much as possible from the viewpoint of thetemperature in the car, and a green type heat absorbing glass is mainlyused at present. This glass slightly reduces transmittance at thevisible light region. Accordingly, also in the case of using the aboveAR film comprising a light absorbing film, it is preferred to make thetransmittance as high as possible and to use it together with a heatabsorbing glass.

However, with respect to a conventionally known absorptive type AR filmfor CRT, the transmittance is considered to be preferably low in orderto improve the contrast, which is one reason to make it difficult toapply the film to a windshield for an automobile.

As another example of the AR film for CRT, a four layer constitution ofglass/transition metal nitride/transparent film/transition metalnitride/transparent film, has been known (U.S. Pat. No. 5,091,244).However, this multi-layer AR film is designed to have a transmittance ofvisible light of 50% or less, and further, the absorbing layer isdivided into two layers to make the number of layers at least fourlayers to achieve this, and thus many steps are required.

Production of a windshield for an automobile most advantageouslycomprises coating on a flat glass substrate, followed by cutting,bending and lamination. However, although it is described that theconventional AR film for CRT may resist heat treatment after coated on apanel glass (such as heat treatment in the frit seal step)(JP-A-9-156964), the temperature for the heat treatment is a level of450° C., and no result of studies has been shown with respect to a hightemperature of from 560 to 700° C. in the step of bending in productionof a windshield for an automobile.

The present invention has been made to overcome the above-describeddrawbacks of the prior art and to provide an antireflection film for awindow of a transport, having an adequately low reflection performanceto oblique incident light (particularly oblique incident light at anangle of a level of 60°), an adequate abrasion resistance and a hightransmittance of visible light, and a glass provided with anantireflection film for a window of a transport comprising saidantireflection film (particularly a glass for an automobile providedwith an antireflection film and a laminated glass for an automobileprovided with an antireflection film).

The present invention further provides an antireflection film for awindow of a transport which presents neutral reflection color tone(color tone close to colorless) to oblique incident light (particularlyoblique incident light at an angle of a level of 60°) and a glassprovided with an antireflection film for a window of a transportcomprising said antireflection film (particularly a glass for anautomobile provided with an antireflection film and a laminated glassfor an automobile provided with an antireflection film).

Further, it is an object of the present invention to provide anantireflection film for a window of a transport which adequately resistsheat treatment (such as heat treatment in the bending step or thetempering step) in production of a glass for an automobile and which isexcellent in productivity at a low cost, and a glass provided with anantireflection film for a window of a transport comprising saidantireflection film (particularly a glass for an automobile providedwith an antireflection film).

Further, it is an object of the present invention to provide a laminatedglass provided with an antireflection film for a window of a transport,comprising the above antireflection film (particularly a laminated glassfor an automobile provided with an antireflection film), and aproduction process to easily obtain a laminated glass provided with anantireflection film for a window of a transport.

DISCLOSURE OF THE INVENTION

The present invention has been made to overcome the above-describedproblems, and provides an antireflection film for a window of atransport, which comprises a light absorbing film consisting essentiallyof a nitride and an oxide film having a refractive index of from 1.45 to1.70 formed on a substrate in this order on the substrate, wherein thegeometrical film thickness of the light absorbing film is from 3 to 12nm, and the geometrical film thickness of the oxide film is from 70 to140 nm (a first invention).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view illustrating the glass providedwith an antireflection film for a window of a transport of Example 1.

FIG. 2 is a graph showing the optical properties of Example 1.

FIG. 3 is a schematic sectional view illustrating the glass providedwith an antireflection film for a window of a transport of Example 2.

FIG. 4 is a glass showing the optical properties of Example 2.

FIG. 5 is a graph showing the optical properties after heat treatment inExample 3.

FIG. 6 is a graph showing the optical properties after glass laminationin Example 3.

FIG. 7 is a schematic sectional view illustrating the state after glasslamination in Example 3.

FIG. 8 is a graph showing the optical properties after heat treatment inExample 4.

FIG. 9 is a graph showing the optical properties after glass laminationin Example 4.

FIG. 10 is a schematic sectional view illustrating the state after glasslamination in Example 4.

FIG. 11 is an explanatory diagram with respect to incident light at anoblique angle in the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The first invention has a constitution consisting essentially of twolayers, but a “barrier film” to prevent oxidation of the light absorbingfilm, is preferably formed between the light absorbing film and theoxide film.

The barrier film has a function to prevent the light absorbing layerformed thereunder from being oxidized in after-heating treatment. Thisis because the barrier film itself contains substantially no oxygen(differently from the oxide film), and in the case where oxygen in theoxide layer formed thereon or oxygen in the air is diffused through theoxide layer, part of the barrier film itself is oxidized, to preventfurther invasion of oxygen.

As the barrier film, a transparent nitride film having a geometricalfilm thickness of from 1 to 20 nm is preferably formed. In addition tothe transparent nitride film, e.g. a film made of at least one metalselected from the group consisting of Si, Ti, Ni—Cr and Zn may be used.The barrier film made of a metal has a geometrical film thickness ofpreferably from 1 to 10 nm.

The barrier film has substantially no optical significance, but it has afunction to impart heat resistance against heat treatment after the filmformation (hereinafter referred to simply as after-heat treatment) suchas after-heat treatment in the bending step or the tempering step inproduction of a glass for an automobile.

The present invention further provides an antireflection film for awindow of a transport, which comprises a light absorbing film consistingessentially of a nitride, a transparent film having a refractive indexof from 1.90 to 2.40, and an oxide film having a refractive index offrom 1.45 to 1.70, formed on a substrate in this order on the substrate,wherein the geometrical film thickness of the light absorbing film isfrom 3 to 12 nm, the geometrical film thickness of the transparent filmhaving a refractive index of from 1.90 to 2.40 is from 40 to 80 nm, andthe geometrical film thickness of the oxide film is from 70 to 140 nm (asecond invention).

The second invention has a constitution consisting essentially of threelayers, and the presence of the transparent film of from 40 to 80 nmhaving a refractive index of from 1.90 to 2.40 (hereinafter referred tosimply as transparent film) will increase the antireflection effect tooblique incident light. Further, at the same time, the heat resistanceagainst the after-heat treatment will increase.

The transparent film is not particularly limited so long as it is madeof a material having a refractive index of from 1.90 to 2.40 at awavelength of 550 nm. For example, an oxide, a nitride or an oxy-nitrideof at least one element selected from the group consisting of Zn, Sn,Ti, Zr, Si, Al, In, Ta, Nb, Bi, W and B, may be mentioned. Particularlypreferred is a transparent nitride film.

The antireflection film of the present invention is formed preferably onthe interior (car interior) side face. For example, when it is used fora laminated glass for a windshield of an automobile consisting of anexterior-side glass substrate and an interior-side glass substrate, itwill be formed on the interior side face of the interior-side glasssubstrate.

FIG. 11 is an explanatory diagram with respect to incident light at anoblique angle in the present invention. When the setting angle of aglass plate to a transport is α°, and the line of sight of an observer(driver) is in the horizontal direction (the observer gazes into theinfinite distance), the line of sight of the observer and the glassplate cross each other at point A, and the angle formed by the line ofsight of the observer and the line perpendicular to the tangent line ofthe glass plate at point A is about (90-α)°.

On the other hand, interior light (such as light around the dashboard10) incident at an angle of about (90-α)° at the point A will reach theobserver, according to Snell laws of reflection.

The angle of incidence of light usually means the angle formed by thedirection perpendicular to the reflection plane and the direction of theincident light. In a case where the setting angle of the glass plate isα°, the angle of incidence of light from the film face side (interiorside) is about (90-α)°. For example, when the setting angle a is 30°,the incident light from the film face side is an incident light at anangle of 60°. Further, the angle of an oblique incident light (dottedline in FIG. 11) from the non-film face side (the side on which no filmis present) is also represented by the angle formed by a lineperpendicular to the tangent line of the glass plate, i.e. about(90-α)°.

The light absorbing film in the present invention (the first and secondinventions) slightly reduces the transmittance, and reduces direct solarradiation heat. Further, when the present invention is applied to aglass for an automobile, the intensity of the reflected light of lightfrom the interior side on the exterior-side glass face will be doublyweakened, and as a result, the contrast in the field of view will beincreased and the visibility of a driver will be increased.

The light absorbing film has an extinction coefficient of preferably atleast 0.05 (particularly preferably at least 0.5) at the visible lightregion. The light absorbing film is preferably a film consistingessentially of at least one metal selected from the group consisting oftitanium, zirconium and hafnium, or a film consisting essentially of anitride of the above metal, from the viewpoint of the dispersionrelation of the extinction coefficient and the refractive index at thevisible light region. Each of the described films may widen thelow-reflection region at the visible light region. It is particularlypreferably a film consisting essentially of a nitride of a metal.

The film consisting essentially of a nitride of a metal may contain aslight amount of oxygen in the film. The content of oxygen significantlyinfluences on the optical constant, and influences on the antireflectionproperty of the antireflection film to be obtained as a final product,and the antireflection property tends to be poor in either case wherethe oxygen content is too high or too low. In the nitride of a metal inthe film, the proportion (ratio in atom) of oxygen to said metal ispreferably at most 0.5. It is particularly preferably at least 0.11.

As the nitride of a metal, titanium nitride is preferred. Titaniumnitride is preferred since 1) it is low-priced, 2) a film can stably beformed, 3) it is excellent in chemical and mechanical durability, and 4)the value of the optical constant at the visible light region wellmatches the transparent nitride film (particularly silicon nitride film)and the oxide film (particularly silicon oxide film) having a refractiveindex of from 1.45 to 1.70, to be formed on the light absorbing film, toreduce the reflectance, and at the same time, the value of theabsorption coefficient is appropriate, and the geometrical filmthickness (hereinafter referred to simply as film thickness) to obtainan appropriate light absorption will be within a range of from severalnm to several tens nm, such being preferred from the viewpoint of bothproductivity and reproducibility.

Titanium nitride is formed into a film preferably by direct-currentsputtering of a metal titanium target in the presence of a nitrogen gas,from the viewpoint of productivity. A small amount of impurities may beincorporated in the target or sputtering gas composition so long as thefilm to be obtained substantially has the optical constant of titaniumnitride.

With respect to titanium nitride, the proportion (ratio in atom) ofnitrogen to titanium in the film is preferably from 0.5 to 1.5 from theviewpoint of the optical constant and the specific resistance. If it isless than 0.5, a rather metallic titanium nitride film will be obtained,and the specific resistance will be low, but the optical constant willbe inappropriate, and the antireflection effect tends to be inadequate.If it exceeds 1.5, a nitrogen-excessive titanium nitride film will beobtained, and the optical constant may change, whereby theantireflection effect tends to be inadequate. Further, with respect totitanium nitride, the proportion (ratio in atom) of oxygen to titaniumin the film is preferably at most 0.5 from the viewpoint of the opticalconstant and the specific resistance. If it exceeds 0.5, an oxy-nitridetitanium film will be obtained, and the optical constant will beinappropriate, whereby the antireflection effect tends to be inadequate.

It is important that the film thickness of the light absorbing film isfrom 3 to 12 nm so as to achieve low-reflection of oblique incidentlight while maintaining a high transmittance. It is particularlypreferably from 3 to 10 nm, more preferably from 3 to 9 nm, furthermorepreferably from 3 to 8 nm, and still furthermore preferably from 3 to 5nm.

To suppress the electromagnetic wave-shielding effect in order to copewith e.g. portable telephones in a car or automatic accounting system,the surface resistance is preferably at least 1.0 kΩ/□, particularlypreferably at least 2 kΩ/□. In the present invention, the lightabsorbing layer is preferably designed to be partially oxidized by theafter-heat treatment to have the above surface resistance.

The oxide film in the present invention (the first and secondinventions) reduces the reflectance by the optical interference with thelight absorbing layer, and at the same time, increases the durability ofthe entire antireflection film by a relatively thick film thickness anda high durability of the oxide film itself.

As the oxide film, a film consisting essentially of an oxide of silicon(Si) is preferred since it has a high durability and a low refractiveindex. Particularly preferred is a silicon oxide film (refractive indexof from about 1.45 to about 1.48 at a wavelength of 550 nm).

In addition, one consisting essentially of an oxide of aluminum (Al), orone consisting essentially of oxides of Si and Al, may, for example, bementioned.

The silicon oxide film is formed preferably by direct current (or radiofrequency) sputtering of a conductive Si target in the presence of anoxygen gas, from the viewpoint of productivity. In this case, a smallamount of impurities may be incorporated in order to let the target haveconductivity. Usually, the silicon oxide film may contain a small amountof impurities (such as Al, B, P and Fe), and an impurity-containingsilicon oxide film having a refractive index substantially the same as asilicon oxide film will also be referred to simply as the silicon oxidefilm.

In the direct current (DC) sputtering of the Si target, arcing is likelyto be induced by charge accumulation on an insulating silicon oxide filmdeposited along the periphery of the eroded region of the target,whereby discharge tends to be unstable, and silicon oxide particlesejected from the arc spot are likely to deposit on the substrate to formdefects. To prevent this and to stabilize the film forming, it is alsopreferred to employ a method of neutralizing the charge by periodicallybringing the cathode to a positive voltage.

It is important that the film thickness of the oxide film in the presentinvention (the first and second inventions) is from 70 to 140 nm fromthe viewpoint of reduction of the reflectance of oblique incident lightand neutralization of the reflection color.

Particularly when it is attempted to increase the antireflection effectto the incident light at an angle of from 40° to 70° from the film faceside, the film thickness of the above oxide film is preferably from 80to 140 nm. Particularly, it is preferably from 95 to 140 nm, morepreferably from 105 to 135 nm, furthermore preferably from 115 to 135nm.

Further, when it is attempted to increase the antireflection effect tothe incident light at an angle of at least 5° and less than 40°, thefilm thickness of the above oxide film is preferably from 70 to 100 nm.

As the transparent nitride film (barrier film) in the first inventionand the transparent nitride film (transparent film) in the secondinvention, preferred is a film having an adequate transparency at thevisible light region (for example, the extinction coefficient at awavelength of 550 nm of at most 0.03, particularly at most 0.01) andhaving excellent chemical durability. Specific examples of its materialinclude a film consisting essentially of a nitride film of at least oneelement selected from the group consisting of silicon, aluminum andboron. The refractive index of the film consisting essentially of theabove nitride film at the visible light region is approximately from 1.9to 2.1. In the second invention, said transparent nitride film plays animportant role on the appearance of low-reflection performance. Saidtransparent nitride film may contain a slight amount of oxygen in thefilm.

The transmittance of visible light (transmittance of visible lightincident at right angles) of the glass provided with an antireflectionfilm is preferably from 70 to 85%. If the transmittance of visible light(hereinafter referred to simply as transmittance) exceeds 85%, theantireflection effect tends to be inadequate, and at the same time, theheat resistance tends to be inadequate. If the transmittance is lessthan 70%, the transmittance of incident light at right angles tends tobe too low, and when said glass is applied to a glass for an automobile,the field of view of a drive is less likely to be secured. Thetransmittance is particularly preferably at least 80%, furthermorepreferably at least 82%. Here, in the present invention, the incidentlight at right angles is the same as the 0° incident light.

In the present invention, the reflectance of incident light at an angleof from 40° to 70° (particularly about 60°) from the film face side onthe film face (in the present invention, “reflectance on the film face”does not include the reflection on the non-film face (the face having nofilm)) is preferably at most 6%. By making it at most 6%, i.e. bylowering by at least about 2% relative to the reflectance (about 8%) onone side of a glass having no coating applied thereto, the reflection ofthe interior will be suppressed. The lower the reflectance of theincident light at an angle of from 40 to 70° (particularly about 60°)from the film face side on the film face, the better. However, to theincident light at an angle of from 40° to 70° (for example, about 60°),the antireflection conditions to the p-polarization component and thes-polarization component of the incident light are different, and thusit is difficult to make the reflectance of sunlight as randompolarization light completely zero. Accordingly, the value of 6% is apractical value.

Further, it is preferred that the reflection color (including thereflection on the non-film face) of the incident light at an angle offrom 40° to 70° (particularly about 60°) from the film face side is moreneutral than the reflection color (including the reflection on thenon-film face) of the incident light at an angle of from 0° to 30° fromthe film face side. By such a reflection color, the visibility improveswhen a driver watches an obliquely mounted windshield of an automobile.Particularly, the reflection color tone is neutral similar to a glasshaving no coating applied thereto, and it can be achieved bypreliminarily optimizing the reflectance and the reflection color toneto the 60° incident light.

When a standard source C according to JIS-Z8722 is used as a lightsource for colorimetry and the color tone of a substance is representedby x and y coordinates, the reflection color to the 60° incident lightand the reflection color to the 30° incident light are preferably suchthat 0.2901≦x≦0.3301 and 0.2962≦y≦0.3362, particularly preferablyx≦0.3201, from the viewpoint of making the color close to neutral.

Here, for a window glass for an automobile, yellowish or reddishreflection color (particularly reddish reflection color) is notpreferred. If both values of x and y are high, the color tends to bedeep yellow, and if the value of x is high, the color tends to be deepred.

The method for forming the light absorbing film, the transparent nitridefilm and the oxide film of the present invention is not particularlylimited, but a sputtering method, particularly a DC sputtering method ispreferred. By using the DC sputtering method, the process can be stablycarried out, and it is thereby easy to form a film of a large area.

As the substrate in the present invention, a glass or a transparentplastic may be used. Particularly, it is preferred to apply the presentinvention by using, as a substrate, a glass to be used for a windshieldof an automobile at the car interior side, since the effect of thepresent invention will adequately be obtained. As the glass, atransparent float glass (a glass produced by float process) or a coloredheat absorbing glass may, for example, be mentioned. Particularly whenthe present invention is applied to a glass for an automobile, it ispreferred to use a heat absorbing glass as a glass substrate from theviewpoint of reducing the energy of direct solar radiation.

The present invention further provides a glass provided with anantireflection film for a window of a transport, comprising a glasssubstrate and the above antireflection film formed on the glasssubstrate; and a glass for an automobile using said glass provided withan antireflection film for a window of a transport. As the glasssubstrate, various types including an uncolored float glass, a coloredfloat glass, a tempered glass and a laminated glass may be used.

The present invention further provides a laminated glass provided withan antireflection film for a window of a transport, wherein the glassprovided with an antireflection film comprising a glass substrate andthe above antireflection film formed on the substrate, is processed tohave a predetermined three-dimensional curved shape by heat treatment,and bonded to another glass substrate by means of an intermediate filmso that the antireflection film faces the interior; and its productionprocess. As the above heat treatment, heat treatment in the bending stepor heat treatment in the tempering step may be mentioned, and it will becarried out, for example, at a temperature of from 560 to 700° C. in theair atmosphere.

The laminated glass provided with an antireflection film for a window ofa transport of the present invention is suitable for a laminated glassfor an automobile (particularly for a laminated glass for a windshieldof an automobile).

In the laminated glass provided with an antireflection film for a windowof a transport of the present invention (hereinafter referred to aslaminated glass of the present invention), the reflectance (includingreflection on the non-film face) of incident light at an angle of 60°from the film face side is preferably at most 11% (particularlypreferably at most 10%).

With respect to the laminated glass for an automobile, the reflectanceof incident light at an angle of 60° from the film face side ispreferably at most 11%, whereas it is about 14% in the case where acolored glass having no coating applied thereto is used (it is about 16%in the case where an uncolored glass is used). Namely, by lowering by atleast about 3% (5% in the case of using an uncolored glass) (i.e. bysuppressing to be about 80% or lower based on the absolute value of thereflectance of the glass having no coating applied thereto), reflectionof the interior will be suppressed. The lower the reflectance of theincident light at an angle of 60° from the film face side, the better.However, as mentioned above, it is difficult to make the reflectance ofthe solar radiation light as random polarized light completely zero.Accordingly, the value of 11% is practical.

Further, when the laminated glass of the present invention is applied toa laminated glass for an automobile, the transmittance of incident lightat right angles from the film face side is preferably at least 70%(particularly preferably at least 75%). With respect to the windshieldof an automobile, the transmittance is defined to be at least 70% inJapan and at least 75% in Europe, in order to secure the visibility ofthe driver.

Further, with respect to the laminated glass of the present invention,the reflectance of incident light at an angle of 60° from the non-filmface side is preferably at least 10% from the viewpoint of heatinsulating properties. By making it at least 10%, the solar radiationheat from the exterior (car exterior) can be prevented by reflection,and the increase in the temperature in the interior (car interior) canbe reduced. Further, it is preferred to employ a windshield having arelatively high reflectance, from the viewpoint of the design of the carin appearance (high grade impression can be obtained). Further, theinterior is less likely to be looked in from the exterior (carexterior), whereby the privacy in the car can be protected.

Further, in the laminated glass of the present invention, thetransmittance of solar radiation to the incident light at right anglesfrom the non-film face side is preferably at most 60%, whereby influx ofsolar energy into the interior (car interior) can be prevented, and thepassengers can comfortably ride in the car. It is particularlypreferably at most 55%.

With the laminated glass of the present invention, it is possible torealize still lower reflection by using the glass provided with anantireflection film of the present invention for the interior-side glassand by using an AR coated glass also for the exterior—(carexterior)—side glass. In such a case, severe abrasion resistance will berequired for the AR coating on the exterior side.

Further, two glass substrates are used for the laminated glass for anautomobile, and the glass substrate on which the antireflection film isformed and/or the other glass substrate is preferably a heat absorbingglass, whereby a low reflection on the interior face can be attained,and at the same time, influx of heat can be suppressed.

Particularly, in the case where the laminated glass of the presentinvention is used as a laminated glass for a windshield of anautomobile, and a heat absorbing glass is used as the glass substrate,the transmittance of solar radiation will be decreased, and theenvironment in the car will be improved, and at the same time,reflection of the dashboard and its surrounding in the car will bereduced for the driver, the front visibility will be improved, and theinterior will be designed more freely.

The glass provided with an antireflection film for a window of atransport of the present invention is suitable particularly for a windowglass for a vehicle. Particularly, it is suitable for a window glass foran automobile (a windshield, a rear glass and a side glass).

EXAMPLE 1

In a vacuum chamber, metal titanium (Ti) and n-type Si (phosphorus-dopedsingle crystal) having a resistivity of 1.2 Ω·cm were set as targets ona cathode, and the vacuum chamber was evacuated to 1.3×10⁻³Pa(1×10⁻⁵Torr). On an uncolored soda-lime glass substrate 1 (thickness: 2mm) set in the vacuum chamber, an antireflection film of the firstinvention was formed on the glass substrate as follows.

(1) Firstly, as a discharge gas, a gas mixture of argon and nitrogen(nitrogen: 10%) was introduced, and conductance was adjusted so that thepressure became 0.27 Pa (2×10⁻³Torr). Then, a negative DC voltage wasapplied to the cathode of Ti to carry out DC sputtering of the Titarget, and a titanium nitride film 2 (light absorbing film: extinctioncoefficient of at least 0.5 at the visible light region, extinctioncoefficient of 1.26 and refractive index of 1.9 at a wavelength of 550nm) of 7.2 nm was formed.

(2) Introduction of the gas was stopped, and the interior of the vacuumchamber was brought to a high level of vacuum. Then, a gas mixture ofargon and nitrogen (nitrogen: 33%) was introduced as a discharge gas,and conductance was adjusted so that the pressure became 0.27 Pa(2×10⁻³Torr). Then, a DC voltage pulsed through SPARCLE-V (manufacturedby ADVANCED ENERGY) from a DC power source was applied to the cathode ofSi, to carry out intermittent DC sputtering of the Si target, and atransparent silicon nitride film 3 (transparent nitride film,corresponding to the barrier film in the present example: extinctioncoefficient of 0.01 and refractive index of 1.93 at a wavelength of 550nm) of 5 nm was formed.

(3) Introduction of the gas was stopped, and the interior of the vacuumchamber was brought to a high level of vacuum. Then, oxygen gas (100%)was introduced as a discharge gas, and conductance was adjusted so thatthe pressure became 0.27 Pa (2×10⁻³Torr). Then, a DC voltage pulsedthrough SPARCLE-V (manufactured by ADVANCED ENERGY) from a DC powersource was applied to the cathode of Si, to carry out intermittent DCsputtering of the Si target, and a silicon oxide film 4 (oxide film,refractive index of about 1.47 at a wavelength of 550 nm) of 122 nm wasformed.

With respect to the obtained glass provided with an antireflection film,the following optical properties 1) to 6) were measured based onJIS-R3106. Namely, 1) transmittance of incident light at an angle ofincidence of 0° (0° T_(v)), 2) reflectance (including reflection on theexterior side (non-film face side)) of incident light at an angle ofincidence of 15° from the interior side (film face side) (→15° interiorR_(v)), 3) reflectance (including reflection on the interior side (filmface side) of incident light at an angle of incidence of 15° from theexterior side (non-film face side) (→15° exterior R_(v)), 4) reflectance(including reflection on the exterior side) of incident light at anangle of incidence of 60° from the interior side (→60° interior R_(v)),5) reflectance on the film face (excluding reflection on the exteriorside) of incident light at an angle of incidence of 60° from theinterior side (→60° film face R_(v)), and 6) transmittance of solarradiation of incident light at right angles from the exterior side(→solar radiation transmittance), were measured. The results are shownin Table 1.

Further, the reflection color was represented by xy coordinates, inaccordance with reflection color evaluation using standard source C inJIS-Z8722 as a light source for colorimetry. The results are shown inTable 1.

Further, the obtained glass provided with an antireflection film was cutinto a square, soldering was carried out linearly on the edges of twosides facing each other by an ultrasonic soldering iron (SUMBONDER SUMIImanufactured by Asahi Glass Company, Limited), and the resistancebetween the solders on the two sides was measured to obtain the surfaceresistance. The results are shown in Table 1.

A schematic sectional view illustrating the obtained glass provided withan antireflection film is shown in FIG. 1. Further, in FIG. 2 are shownthree spectral curves of a spectral transmittance curve of the glassprovided with an antireflection film at an angle of incidence of 60°, aspectral reflectance curve (dotted line) of the glass provided with anantireflection film at an angle of incidence of 60° on the film faceside and a spectral reflectance curve (solid line) of the glass providedwith an antireflection film at an angle of incidence of 60° on the glassface side.

Further, the constitution of the glass provided with an antireflectionfilm of Example 1 is shown in Table 2. Each of the constitutions in thefollowing Examples is also shown in Table 2. In Table 2, “TiN”represents the titanium nitride film, “SiN” the transparent siliconnitride film, and “SiO₂” the silicon oxide film, and “clear” representsan uncolored soda-lime glass substrate, “green” a heat absorbing glass(SUNGREEN manufactured by Asahi Glass Company, Limited) and “highlyabsorbing green” a highly heat absorbing glass (UV GREEN manufactured byAsahi Glass Company, Limited). Values in brackets represent thethickness.

EXAMPLE 2

Film forming was carried out in a same manner as in Example 1 exceptthat the film thicknesses of the light absorbing film and thetransparent nitride film in Example 1 were changed, to form anantireflection film of the second invention on the glass substrate 1.Namely, in the present Example, a titanium nitride film 2 (lightabsorbing film) of 5 nm, a transparent silicon nitride film 5(transparent nitride film) of 62.5 nm and a silicon oxide film 4 (oxidefilm ) of 122 nm were formed in this order.

The obtained glass provided with an antireflection film was evaluated inthe same manner as in Example 1. The results are shown in Table 1. Aschematic sectional view illustrating the obtained glass provided withan antireflection film is shown in FIG. 3. Further, three spectralcurves are shown in FIG. 4 in the same manner as in Example 1.

EXAMPLE 3

The glass provided with an antireflection film obtained in Example 1 wassubjected to bending as follows. Namely, the glass provided with anantireflection film obtained in Example 1, and a heat absorbing glass 7(green glass “SUNGREEN” manufactured by Asahi Glass Company, Limited,having a thickness of 2 mm and washed with pure water) having the samesize as said glass, were prepared. The two glasses were overlaid so thatthe glass provided with an antireflection film was on the upper side andthe other glass was on the lower side, and the antireflection film facefaced upward. Between the two glasses, a powder for preventing heat sealwas spread.

The two glasses were put on a mold for forming, and heat treatment wascarried out in an electric heating furnace for bending. The heattreatment was carried out in the air atmosphere under such conditionsthat the preheating time was 3 minutes, the maximum temperature holdingtime was 5 minutes, the maximum achievable temperature of the glass was620° C. and the slow cooling time was 3 minutes.

No wrinkle or change in color was shown on the antireflection film, andno extraordinary warp of the glass plate was shown. The two glasses werefitted in the mold well, and subjected to bending. The glass providedwith an antireflection film after the heat treatment was evaluated. Theresults are shown in Table 1. Blank columns in Table 1 represent that nomeasurement was carried out. Further, three spectral curves are shown inFIG. 5 in the same manner as in Example 1.

Then, the two glasses subjected to bending were laminated by means of anintermediate film (polyvinyl butyral) having a thickness of 0.76 mm, toform a laminated glass. A schematic sectional view illustrating theobtained laminated glass is shown in FIG. 7. The obtained laminatedglass was evaluated in the same manner as in Example 1. The results areshown in Table 1. In Table 1, said results are shown in the column “Ex.3 after lamination” (the same applies hereinafter). Further, threespectral curves are shown in FIG. 6 in the same manner as in Example 1.

EXAMPLE 4

Bending was carried out in the same manner as in Example 3 except that“the glass provided with an antireflection film obtained in Example 2”was used instead of “the glass provided with an antireflection filmobtained in Example 1” in Example 3, and the glass provided with anantireflection film after the heat treatment was evaluated. The resultsare shown in Table 1. Three spectral curves are shown in FIG. 8 in thesame manner as in Example 1.

Then, a laminated glass was formed in the same manner as in Example 3,and evaluation was carried out in the same manner as in Example 1. Theresults are shown in Table 1. A schematic sectional view illustratingthe obtained laminated glass is shown in FIG. 10. Further, threespectral curves are shown in FIG. 9 in the same manner as in Example 1.

EXAMPLE 5

Film forming was carried out in the same manner as in Example 1 exceptthat the film thicknesses of the light absorbing film and thetransparent oxide film in Example 1 were changed, and no transparentnitride film in Example 1 (barrier film in Example 1) was formed, toform an antireflection film of the first invention on a glass substrate.Namely, in the present Example, a titanium nitride film (light absorbingfilm) of 4 nm and a silicon oxide film (oxide film) of 115 nm wereformed in this order.

The obtained glass provided with an antireflection film was evaluated inthe same manner as in Example 1. The results are shown in Table 1.

EXAMPLE 6

Bending was carried out in the same manner as in Example 3 except that“the glass provided with an antireflection film obtained in Example 5”was used instead of “the glass provided with an antireflection filmobtained in Example 1” in Example 3, and then a laminated glass wasformed in the same manner as in Example 3. The optical properties weremeasured in the same manner as in Example 1, and the results are shownin Table 1.

Then, a laminated glass was formed in the same manner as in Example 3,and evaluated in the same manner as in Example 1. The results are shownin Table 1.

EXAMPLE 7

Film forming was carried out on a glass substrate in the same manner asin Example 1 except that the film thicknesses of the light absorbingfilm and the oxide film in Example 1 were changed. Namely, in thepresent Example, a titanium nitride film (light absorbing film) of 10nm, a transparent silicon nitride film (transparent nitride film) of 5nm and a silicon oxide film (oxide film) of 85 nm were formed in thisorder.

With respect to the obtained glass provided with an antireflection film,the optical properties were measured in the same manner as in Example 1.The results are shown in Table 1.

EXAMPLE 8

Bending was carried out in the same manner as in Example 3 except that“the glass provided with an antireflection film obtained in Example 7”was used instead of “the glass provided with an antireflection filmobtained in Example 1” in Example 3, and an uncolored soda-lime glass(thickness: 2 mm) having a thickness of 2 mm was used instead of “theheat absorbing glass” in Example 3. With respect to the glass providedwith an antireflection film after the heat treatment, the opticalproperties were measured. The results are shown in Table 1.

Then, a laminated glass was obtained in the same manner as in Example 3.The obtained laminated glass was evaluated in the same manner as inExample 1, and the results are shown in Table 1.

EXAMPLE 9

Film forming was carried out in the same manner as in Example 1 exceptthat the film thicknesses in Example 1 were changed, to form anantireflection film of the first invention on a glass substrate 1.Namely, in the present Example, a titanium nitride film (light absorbingfilm) of 4 nm, a transparent silicon nitride film (barrier film) of 5 nmand a silicon oxide film (oxide film) of 90 nm were formed in thisorder.

The obtained glass provided with an antireflection film was evaluated inthe same manner as in Example 1 except that the optical properties withrespect to “the incident light at an angle of incidence of 30°” wereevaluated instead of the optical properties with respect to “theincident light at an angle of incidence of 60°” in Example 1, and theresults are shown in Table 1.

EXAMPLE 10

Bending was carried out in the same manner as in Example 3 on the glassprovided with an antireflection film obtained in Example 9, except that“the glass provided with an antireflection film obtained in Example 9”was used instead of “the glass provided with an antireflection filmobtained in Example 1” in Example 3, and “a highly heat absorbing glass(UV COOLGREEN manufactured by Asahi Glass Company, Limited) having athickness of 2 mm” was used instead of “the heat absorbing glass” inExample 3. Then, the glass provided with an antireflection film afterthe heat treatment was evaluated in the same manner as in Example 9. Theresults are shown in Table 1.

Then, a laminated glass was obtained in the same manner as in Example 3.The obtained laminated glass was evaluated in the same manner as inExample 9. The results are shown in Table 1.

Comparative Example 1

Film forming was carried out on a glass substrate in the same manner asin Example 1 except that the film thicknesses of the light absorbingfilm and the oxide film in Example 1 were changed. Namely, in thepresent Example, a titanium nitride film (light absorbing film) of 13nm, a transparent silicon nitride film (transparent nitride film) of 5nm and a silicon oxide film (oxide film) of 85 nm were formed in thisorder.

With respect to the obtained glass provided with an antireflection film,the optical properties were measured in the same manner as in Example 1.The results are shown in Table 1.

Comparative Example 2

Bending was carried out in the same manner as in Example 3 except that“the glass provided with an antireflection film obtained in ComparativeExample 1” was used instead of “the glass provided with anantireflection film obtained in Example 1” in Example 3, and anuncolored soda-lime glass (thickness: 2 mm) having a thickness of 2 mmwas used instead of “the heat absorbing glass” in Example 3. Withrespect to the glass provided with an antireflection film after the heattreatment, the optical properties were measured. The results are shownin Table 1.

Then, a laminated glass was obtained in the same manner as in Example 3.The obtained laminated glass was evaluated in the same manner as inExample 1. The results are shown in Table 1.

Comparative Example 3

Two sheets of heat absorbing glass (two sheets of green glass having athickness of 2 mm and washed with pure water, i.e. “SUNGREEN” and “UVCOOLGREEN” manufactured by Asahi Glass Company, Limited, respectively)were laminated by means of an intermediate film (polyvinyl butyral)interposed therebetween, to form a laminated glass. With respect to theobtained laminated glass, the optical properties were measured in thesame manner as in Example 1. The results are shown in Table 1.

Comparative Example 4

Two sheets of heat absorbing glass (two sheets of green glass having athickness of 2 mm and washed with pure water, i.e. two sheets of“SUNGREEN” manufactured by Asahi Glass Company, Limited) were laminatedby means of an intermediate film (polyvinyl butyral) having a thicknessof 0.76 mm, to form a laminated glass. With respect to the obtainedlaminated glass, the optical properties were measured in the same manneras in Example 1. The results are shown in Table 1.

Comparative Example 5

With respect to the laminated glass obtained in Comparative Example 3,the optical properties with respect to “the incident light at an angleof incidence of 30°” were evaluated instead of the optical propertieswith respect to “the incident light at an angle of incidence of 60°” inComparative Example 3, and the results are shown in Table 1 asComparative Example 5.

From Table 1, it is found that the antireflection films obtained inExamples 1 to 10, are excellent in heat resistance, have lowreflectances 60° of the incident light (60° interior R_(v) and 60° filmface R_(v)), and provide more neutral reflection color tone, althoughthey have a simple film constitution.

With respect to the antireflection films obtained in ComparativeExamples 1 and 2, the value of x to the incident light at an angle of60° is high, and the reflection color tends to be red, which is not apreferred color tone.

The antireflection films obtained in Comparative Examples 1 and 2, havea transmittance of visible light of less than 70%, and they are notsuitable for a windshield of an automobile.

Further, the laminated glasses obtained in Examples 3, 4, 6, 8 and 10,have a low reflectance on the film face side (i.e. interior side), ascompared with the laminated glasses (Comparative Examples 3, 4 and 5)using a heat absorbing glass having no film formed thereon.

Further, in the glass provided with an antireflection film having abarrier film of Example 1, the change in transmittance before and afterthe heat treatment is small.

Further, the antireflection films obtained in Examples 9 and 10, areexcellent in heat resistance, and have low reflectances of 30° incidentlight (30° interior R_(v) and 30° film face R_(v)), although they have asimple film constitution. The values of 30° interior R_(v) and 30° filmface R_(v) are extremely low as compared with the laminated glass usinga heat absorbing glass having no film formed thereon (ComparativeExample 5). Further, the transmittance of solar radiation also shows alow value of at most 50%.

The reflection color (including reflection on the non-film face side) bythe incident light at an angle of 15° from the film face side and thereflection color (including reflection on the non-film face side) by theincident light at an angle of 60° from the film face side were comparedwith each other with respect to Examples 3, 4 and 6 wherein the glasslamination was carried out, whereupon the reflection color by theincident light at an angle of 60° from the film face side became moreneutral.

Further, abrasion resistance was checked with respect to theantireflection film face in each of Examples 1 to 10. Namely, abrasiontest was carried out by a Taber abrader at a load of 2.45N at 500revolutions in accordance with JIS-R3212. No peeling of the film wasshown after the abrasion test, the haze value was at most 3% in allcases, and practically adequate abrasion resistance was confirmed.

Further, with respect to the antireflection films obtained in Examples 1to 10, chemical durability was evaluated. Namely, the 0° T_(v) and the60° film face R_(v) were measured before and after impregnation in 0.1mol/l of aqueous sodium hydroxide solution at room temperature for 2hours, and as a result, the values were not changed, whereby anexcellent alkali resistance was confirmed. Further, the 0° T_(v) and the60° film face R_(v) were measured before and after impregnation in 0.05mol/l of aqueous sulfuric acid solution at room temperature for 2 hours,and as a result, the values were not changed, whereby an excellent acidresistance was confirmed.

A windshield for an automobile was formed by using a glass substrate foran automobile as the glass substrate, by forming an antireflection filmin the same manner as in Example 1, and by carrying out glass laminationin the same manner as in Example 3. The optical properties were measuredin the same manner as in Example 1, and excellent optical propertieswere obtained.

TABLE 1 Solar 15° 15° 60° 60° radiation Film Interi- Exteri- 15° 15°Interi- Exteri- 60° Film 60° 60° transmit- resist- 0° T_(v) or R_(v) orR_(v) Interi- Interi- or R_(v) or R_(v) face R_(v) Inter- Interi- tanceance % % % or x or y % % % or x or y % KΩ/□ Ex. 1 74.4 5.5 8.7 10.3 16.5 5.1 65.1 0.8 Ex. 2 76.2 5.4 9.8 9.2 14.6 3.7 68.5 1.0 Ex. 3 76.64.7 8.7 10.4  16.2 5.2 66.7 1.6 Ex. 3 after 70.2 4.5 7.8 0.2693 0.29189.5 15.6 5.2 0.3065 0.3332 49.8 1.6 lamination Ex. 4 79.4 3.7 6.7 9.514.2 3.6 70.2 2.0 Ex. 4 after 71.6 3.7 7.2 0.2169 0.2083 8.5 10.8 3.60.3114 0.3072 51.1 2.0 lamiation Ex. 5 78.1 5.2 9.0 10.5  15.3 5.4 70.21.1 Ex. 6 81.3 5.5 8.5 10.8  15.0 5.8 74.0 2.2 Ex. 6 after 75.0 5.1 8.00.2781 0.3050 9.8 14.0 5.8 0.3038 0.3303 53.9 2.2 lamnation Ex. 7 71.54.0 10.3  9.5 15.8 5.5 60.1 0.4 Ex. 8 73.5 3.2 10.0  9.9 15.6 5.7 62.50.8 Ex. 8 after 71.4 3.2 9.8 0.2974 0.3197 9.8 15.3 5.7 0.3192 0.339359.3 0.8 lamination Comp. Ex. 1 64.8 2.2 12.9  8.3 18.8 4.9 53.4 0.3Comp. Ex. 2 66.5 2.2 12.4  8.6 16.6 4.9 55.2 0.6 Comp. Ex. 2 65.3 2.212.1  8.4 16.3 5.0 0.3263 0.3426 52.4 0.6 after lamination Comp. Ex. 375.3 6.8 6.8 0.3044 0.3340 13.3  13.3 7.5 0.3053 0.3342 48.1 Comp. Ex. 478.5 7.0 7.0 0.3043 0.3354 13.6  13.6 9.3 0.3062 0.3334 53.8 Solar 15°15° 30° 30° radiation Film Interi- Exteri- 15° 15° Interi- Exteri- 30°Film 30° 30° transmit- resist- 0° T_(v) or R_(v) or R_(v) Inter- Interi-or R_(v) or R_(v) face R_(v) Inter- Interi- tance ance % % % or x or y %% % or x or y % KΩ/□ Ex. 9 79.4 3.9 9.0 4.1 9.0 0.9 70.9 1.1 Ex. 10 82.24.6 8.5 4.7 8.5 1.1 74.6 2.2 Ex. 10 71.1 3.5 8.2 0.2827 0.3160 3.5 8.21.1 0.3103 0.3406 47.1 2.2 after lamination Comp. Ex. 5 75.3 6.8 6.80.3044 0.3340 7.0 7.0 4.2 0.3054 0.333 48.1

TABLE 2 Another substrate Constitution laminated by means ofSubstrate/first layer/second layer/third layer an intermediate film Ex.1 Clear(2 mm)/TiN(7.2 nm)/SiN(5 nm)/SiO2(122 nm) Nil Ex. 2 Clear(2mm)/TiN(5 nm)/SiN(62.5 nm)/SiO2(122 nm) Nil Ex. 3 Clear(2 mm)/TiN(7.2nm)/SiN(5 nm)/SiO2(122 nm) Nil Ex. 3 after lamination Clear(2mm)/TiN(7.2 nm)/SiN(5 nm)/SiO2(122 nm) Green (2 mm) Ex. 4 Clear(2mm)/TiN(5 nm)/SiN(62.5 nm)/SiO2(122 nm) Nil Ex. 4 after laminationClear(2 mm)/TiN(5 nm)/SiN(62.5 nm)/SiO2(122 nm) Green (2 mm) Ex. 5Clear(2 mm)/TiN(4 nm)/ SiO2(115 nm) Nil Ex. 6 Clear(2 mm)/TiN(4 nm)/SiO2(115 nm) Nil Ex. 6 after lamination Clear(2 mm)/TiN(4 nm)/ SiO2(115nm) Green (2 mm) Ex. 7 Clear(2 mm)/TiN(10 nm)/SiN(5 nm)/SiO2(85 nm) NilEx. 8 Clear(2 mm)/TiN(10 nm)/SiN(5 nm)/SiO2(85 nm) Nil Ex. 8 afterlamination Clear(2 mm)/TiN(10 nm)/SiN(5 nm)/SiO2(85 nm) Clear (2 mm)Comp. Ex. 1 Clear(2 mm)/TiN(13 nm)/SiN(5 nm)/SiO2(85 nm) Nil Comp. Ex. 2Clear(2 mm)/TiN(13 nm) /SiN(5 nm) /SiO2 (85 nm) Nil Comp. Ex. 2 afterlamination Clear(2 mm)/TiN(13 nm)/SiN(5 nm)/SiO2(85 nm) Clear (2 mm)Comp. Ex. 3 Highly absorbing green (2 mm) Green (2 mm) Comp. Ex. 4 Green(2 mm) Green (2 mm) Ex. 9 Clear(2 mm)/TiN(4 nm)/SiN(5 nm)/SiO2 (90 nm)Nil Ex. 10 Clear(2 mm)/TiN(4 nm)/SiN(5 nm)/SiO2 (90 nm) Nil Ex. 10 afterlamination Clear(2 mm)/TiN(4 nm)/SiN(5 nm)/SiO2 (90 nm) Highly absorbinggreen (2 mm) Comp. Ex. 5 Highly absorbing green (2 mm) Green (2 nm)

INDUSTRIAL APPLICABILITY

The antireflection film of the present invention has an adequately lowreflection performance to the oblique incident light, an adequateabrasion resistance and a high transmittance of visible light.

Accordingly, when the antireflection film of the present invention isused for a windshield for an automobile, reflection of the dashboard andits surrounding in the car will be reduced for the driver, and the frontvisibility will be improved, and at the same time, the interior will bedesigned more freely. Further, by employing a specific constitution, thereflection color to the oblique incident light can be made neutral.

Further, the antireflection film of the present invention has a totalfilm thickness of at most half the conventional transparent multi-layerAR film, and thus the production cost will be reduced.

Further, the antireflection film of the present invention has a hightransmittance, is suitable for a windshield for an automobile using aheat absorbing glass, and makes it possible to satisfy both heatshielding property and low reflection property.

Further, the antireflection film of the present invention has a thickoxide film, and it is thereby excellent in abrasion resistance.Accordingly, when the antireflection film of the present invention isused for a window of a transport on the interior (car interior) side, awindow of a transport (particularly window glass for an automobile)having adequate chemical and mechanical durability will be provided. Theabove durability is so high that application to a door glass for anautomobile is possible.

Further, the antireflection film of the present invention adequatelyresists heat treatment in production of a glass for an automobile (e.g.heat treatment in bending step or tempering step), and it is therebypossible to carry out after-heat treatment. Accordingly, by using theantireflection film of the present invention, a laminated glass for awindow of a transport, particularly a laminated glass for a windshieldof an automobile, can be easily produced by steps of film forming on aflat glass substrate, cutting, bending and lamination in this order, ata reduced cost with a high productivity.

What is claimed is:
 1. A window of a transport, which comprises asubstrate, and a light absorbing film consisting essentially of anitride and an oxide film having a refractive index of from 1.45 to 1.70formed on the substrate in this order on the substrate, wherein thegeometrical film thickness of the light absorbing film is from 3 to 12nm, and the geometrical film thickness of the oxide film is from 70 to140 nm.
 2. The window of a transport according to claim 1, wherein atransparent nitride film having a geometrical film thickness of from 1to 20 nm is formed between the light absorbing film and the oxide film.3. The window of a transport according to claim 2, wherein thereflectance of visible light incident at an angle of from 40° to 70°from the film face side is at most 6% on the film face.
 4. The window ofa transport according to claim 2, wherein the substrate is a glasssubstrate.
 5. The window of a transport of claim 4, wherein thetransport is an automobile.
 6. The laminated glass for a window of atransport, which comprises the glass substrate provided with anantireflection film for a window of a transport of claim 4, heat-treatedto have a predetermined three-dimensional curve shape, and having asecond glass substrate bonded to said glass substrate by means of anintermediate film so that the antireflection film faces the interior ofsuch transport.
 7. The laminated glass provided with an antireflectionfilm for a window of a transport according to claim 4, wherein thereflectance of visible light incident at an angle of 60° from the filmface side is at most 11%.
 8. A process for producing a laminated glassprovided with an antireflection film for a window of a transport, whichcomprises heat-treating the glass substrate having an antireflectionfilm for a window of a transport of claim 4 to form a predeterminedthree-dimensional curved shape, and then bonding said heat-treated glasssubstrate having an antireflection film to another glass substrate bymeans of an intermediate film so that the antireflection film faces theinterior of said transport.
 9. The window of a transport of claim 4,wherien the glass substrate is a heat absorbing glass.
 10. The window ofa transport of claim 9, wherein the transport is an automobile.
 11. Thelaminated glass for a window of a transport, which comprises the glasssubstrate provided with an antireflection film for a window of atransport of claim 9, heat-treated to have a predeterminedthree-dimensional curve shape, and having a second glass substratebonded to said glass substrate by means of an intermediate film so thatthe antireflection film faces the interior of such transport.
 12. Thelaminated glass provided with an antireflection film for a window of atransport according to claim 9, wherein the reflectance of visible lightincident at an angle of 60° from the film face side is at most 11%. 13.A process for producing a laminated glass provided with anantireflection film for a window of a transport, which comprisesheat-treating the glass substrate having an antireflection film for awindow of a transport of claim 9 to form a predeterminedthree-dimensional curved shape, and then bonding said heat-treated glasssubstrate having an antireflection film to another glass substrate bymeans of an intermediate film so that the antireflection film faces theinterior of said transport.
 14. The window of a transport according toclaim 1, wherein the reflectance of visible light incident at an angleof from 40° to 70° from the film face side is at most 6% on the filmface.
 15. The window of a transport of claim 14, wherein the substrateis a glass substrate.
 16. The window of a transport of claim 15, whereinthe transport is an automobile.
 17. The laminated glass for a window ofa transport, which comprises the glass substrate provided with anantireflection film for a window of a transport of claim 15,heat-treated to have a predetermined three-dimensional curve shape, andhaving a second glass substrate bonded to said glass substrate by meansof an intermediate film so that the antireflection film faces theinterior of such transport.
 18. The laminated glass provided with anantireflection film for a window of a transport according to claim 15,wherein the reflectance of visible light incident at an angle of 60°from the film face side is at most 11%.
 19. A process for producing alaminated glass provided with an antireflection film for a window of atransport, which comprises heat-treating the glass substrate having anantireflection film for a window of a transport of claim 15 to form apredetermined three-dimensional curved shape, and then bonding saidheat-treated glass substrate having an antireflection film to anotherglass substrate by means of an intermediate film so that theantireflection film faces the interior of said transport.
 20. The windowof a transport of claim 15, wherien the glass substrate is a heatabsorbing glass.
 21. The window of a transport of claim 20, wherein thetransport is an automobile.
 22. The laminated glass for a window of atransport, which comprises the glass substrate provided with anantireflection film for a window of a transport of claim 20,heat-treated to have a predetermined three-dimensional curve shape, andhaving a second glass substrate bonded to said glass substrate by meansof an intermediate film so that the antireflection film faces theinterior of such transport.
 23. The laminated glass provided with anantireflection film for a window of a transport according to claim 20,wherein the reflectance of visible light incident at an angle of 60°from the film face side is at most 11%.
 24. A process for producing alaminated glass provided with an antireflection film for a window of atransport, which comprises heat-treating the glass substrate having anantireflection film for a window of a transport of claim 20 to form apredetermined three-dimensional curved shape, and then bonding saidheat-treated glass substrate having an antireflection film to anotherglass substrate by means of an intermediate film so that theantireflection film faces the interior of said transport.
 25. The windowof a transport of claim 1, wherein the substrate is a glass substrate.26. The window of a transport of claim 25, wherein the glass substrateis a heat absorbing glass.
 27. The window of a transport of claim 26,wherein the transport is an automobile.
 28. The laminated glass for awindow of a transport, which comprises the glass substrate provided withan antireflection film for a window of a transport of claim 26,heat-treated to have a predetermined three-dimensional curve shape, andhaving a second glass substrate bonded to said glass substrate by meansof an intermediate film so that the antireflection film faces theinterior of such transport.
 29. A process for producing a laminatedglass provided with an antireflection film for a window of a transport,which comprises heat-treating the glass substrate having anantireflection film for a window of a transport of claim 26 to form apredetermined three-dimensional curved shape, and then bonding saidheat-treated glass substrate having an antireflection film to anotherglass substrate by means of an intermediate film so that theantireflection film faces the interior of said transport.
 30. The windowof a transport of claim 25, wherein the transport is an automobile. 31.The laminated glass provided with an antireflection film for a window ofa transport according to claim 30, wherein the reflectance of visiblelight incident at an angle of 60° from the film face side is at most11%.
 32. A laminated glass for a window of a transport, which comprisesthe glass substrate provided with an antireflection film for a window ofa transport of claim 25, heat treated to have a predeterminedthree-dimensional curve shape, and having a second glass substratebonded to said glass substrate by means of an intermediate film so thatthe antireflection film faces the interior of said transport.
 33. Aprocess for producing a laminated glass provided with an antireflectionfilm for a window of a transport, which comprises heat treating theglass substrate having an antireflection film for a window of atransport of claim 25 to form a predetermined three-dimensional curvedshape, and then bonding said heat treated glass substrate having anantireflection film to another glass substrate by means of anintermediate film so that the antireflection film faces the interior ofsaid transport.
 34. An antireflection film on a window of a transport,which comprises a light absorbing film consisting essentially of anitride, a transparent film having a refractive index of from 1.90 to2.40, and an oxide film having a refractive index of from 1.45 to 1.70,formed on a substrate in this order on the substrate, wherein thegeometrical film thickness of the light absorbing film is from 3 to 12nm, the geometrical film thickness of the transparent film having arefractive index of from 1.90 to 2.40 is from 40 to 80 nm, and thegeometrical film thickness of the oxide film is from 70 to 140 nm. 35.An antireflection film on a window of a transport according to claim 34,wherein the reflectance of visible light at an angle of from 40° to 70°from the film face side is at most 6% on the film face.
 36. Theantireflection film on a window of a transport according to claim 34,wherein the substrate is a glass substrate.
 37. The antireflection filmon a window of a transport of claim 36, wherein the glass substrate is aheat absorbing glass.
 38. The antireflection film on a window of atransport of claim 37, wherein the transport is an automobile.
 39. Thelaminated glass for a window of a transport, which comprises the glasssubstrate provided with an antireflection film on a window of atransport of claim 37, heat-treated to have a predeterminedthree-dimensional curve shape, and having a second glass substratebonded to said glass substrate by means of an intermediate film so thatthe antireflection film faces the interior of such transport.
 40. Thelaminated glass provided with an antireflection film on a window of atransport according to claim 37, wherein the reflectance of visiblelight incident at an angle of 60° from the film face side is at most11%.
 41. A process for producing a laminated glass provided with anantireflection film for a window of a transport, which comprisesheat-treating the glass substrate having an antireflection film on awindow of a transport of claim 37 to form a predeterminedthree-dimensional curved shape, and then bonding said heat-treated glasssubstrate having an antireflection film to another glass substrate bymeans of an intermediate film so that the antireflection film faces theinterior of said transport.
 42. The antireflection film on a window of atransport of claim 30, wherein the transport is an automobile.
 43. Thelaminated glass for a window of a transport, which comprises the glasssubstrate provided with an antireflection film on a window of atransport of claim 36, heat-treated to have a predeterminedthree-dimensional curve shape, and having a second glass substratebonded to said glass substrate by means of an intermediate film so thatthe antireflection film faces the interior of such transport.
 44. Thelaminated glass provided with an antireflection film on a window of atransport according to claim 36, wherein the reflectance of visiblelight incident at an angle of 60° from the film face side is at most11%.
 45. A process for producing a laminated glass provided with anantireflection film on a window of a transport, which comprisesheat-treating the glass substrate having an antireflection film for awindow of a transport of claim 36 to form a predeterminedthree-dimensional curved shape, and then bonding said heat-treated glasssubstrate having an antireflection film to another glass substrate bymeans of an intermediate film so that the antireflection film faces theinterior of said transport.